U.S. patent number 6,443,241 [Application Number 09/518,122] was granted by the patent office on 2002-09-03 for pipe running tool.
This patent grant is currently assigned to Varco I/P, Inc.. Invention is credited to George Boyadjieff, Brian L. Eidem, Daniel Juhasz, Hans Van Rijzingen.
United States Patent |
6,443,241 |
Juhasz , et al. |
September 3, 2002 |
**Please see images for:
( Certificate of Correction ) ** |
Pipe running tool
Abstract
A pipe running tool for use in an oil drilling system and the
like comprises a lower drive shaft adapted to engage a drive shaft
of a top drive assembly for rotation therewith. The pipe running
tool further includes a lower pipe engagement assembly which is
driven to rotate by the lower drive shaft, and is designed to
releasably engage a pipe segment in such a manner to substantially
prevent relative rotation between the two. Thus, when the lower
pipe engagement assembly is actuated to securely hold a pipe
segment, the top drive assembly may be actuated to rotate the top
drive output shaft, which causes the lower drive shaft and lower
pipe engagement assembly to rotate, which in turn rotates the pipe
segment.
Inventors: |
Juhasz; Daniel (Westminister,
CA), Boyadjieff; George (Bell Park, CA), Eidem; Brian
L. (Cerritos, CA), Van Rijzingen; Hans (Etten-Leur,
NL) |
Assignee: |
Varco I/P, Inc. (Houston,
TX)
|
Family
ID: |
22405604 |
Appl.
No.: |
09/518,122 |
Filed: |
March 3, 2000 |
Current U.S.
Class: |
175/52;
166/77.51; 175/85 |
Current CPC
Class: |
E21B
19/00 (20130101); E21B 19/02 (20130101); E21B
19/07 (20130101); E21B 19/086 (20130101); E21B
19/165 (20130101); E21B 19/14 (20130101); E21B
19/16 (20130101); E21B 19/164 (20130101); E21B
19/10 (20130101) |
Current International
Class: |
E21B
3/02 (20060101); E21B 19/14 (20060101); E21B
19/086 (20060101); E21B 3/00 (20060101); E21B
19/10 (20060101); E21B 19/16 (20060101); E21B
19/07 (20060101); E21B 19/00 (20060101); E21B
19/02 (20060101); E21B 019/06 () |
Field of
Search: |
;175/52,85,162
;166/77.51,77.52,77.53,85.1 ;414/22.51 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
0 311 455 |
|
Apr 1989 |
|
EP |
|
0 525 247 |
|
Feb 1993 |
|
EP |
|
96/18799 |
|
Jun 1996 |
|
WO |
|
98/11322 |
|
Mar 1998 |
|
WO |
|
WO 99/30000 |
|
Jun 1999 |
|
WO |
|
Other References
International Search Report relating to corresponding International
Application No. PCT/US00/05752 dated Sep. 28, 2000. .
Invitation to Pay Additional Fees relating to corresponding
International Application No. PCT/US00/05752 dated Jun. 30, 2000.
.
Kamphorst, Herman and Bottger, Dietrich; Casing Running Tool; A
feasibility study; QCD Management and Consultancy; pp. 1-30. .
Kamphorst, G.H., van Wechen, G.L., Bottger, D., and Koch, K.;
Casing Running Tool; SPE/IADC 52770; pp. 1-9..
|
Primary Examiner: Neuder; William
Attorney, Agent or Firm: Christie, Parker & Hale,
LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION(S)
This application is based on provisional patent application Ser.
No. 60/122,915 filed Mar. 5, 1999.
Claims
What is claimed is:
1. A pipe running tool mountable on a rig and designed for use in
handling pipe segments and for engaging pipe segments to a pipe
string, the pipe running tool comprising: a top drive assembly
adapted to be connected to the rig, the top drive assembly
including a top drive output shaft, the top drive assembly being
operative to rotate the drive shaft; a lower drive shaft coupled to
the top drive output shaft and comprising an adjustable segment
that is selectively adjustable to adjust the length of the second
drive shaft; a lower pipe engagement assembly including a central
passageway sized for receipt of the pipe segment, the lower pipe
engagement assembly being operative to releasably grasp the pipe
segment, the lower pipe engagement assembly being connected to the
second drive shaft, whereby actuation of the top drive assembly
causes the lower pipe engagement assembly to rotate; and means for
applying a force to the second shaft to cause the length of the
adjustable segment to be shortened.
2. The pipe running tool of claim 1, wherein the means for applying
comprises a load compensator in the form of a pair of hydraulic
cylinders.
3. The pipe running tool of claim 1, wherein the lower pipe
engagement assembly is actuated by one of a hydraulic system and a
pneumatic system.
4. The pipe running tool of claim 1, wherein the lower pipe
engagement assembly comprises a generally cylindrical housing
defining a central passage, and a plurality of slips disposed
within the housing and displaceable radially inwardly to engage a
casing segment extending through the passage.
5. The pipe running tool of claim 1, further including a block
connected to the top drive assembly and adapted for engaging a
plurality of cables connected to the rig to selectively raise and
lower the top drive assembly.
6. The pipe running tool of claim 1, further including a hoist
mechanism connected to the lower pipe engagement assembly and
operative to hoist a pipe segment into the central passageway of
the lower pipe engagement assembly.
7. The pipe running tool of claim 6, wherein the hoist mechanism
comprises an axle journaled to the lower pipe engagement member, a
pair of pulleys rotatably mounted to the axle, and a gear connected
to the axle, whereby the gear may be coupled to a drive system for
rotating the axle.
8. The pipe running tool of claim 7, wherein the drive system
comprises at least one hydraulic lift cylinder.
9. The pipe running tool of claim 1, wherein the lower pipe
engagement assembly comprises a spider/elevator.
10. A pipe running tool mountable on a rig and designed for use in
connection with a top drive assembly adapted to be connected to the
rig for vertical displacement of the top drive assembly relative to
the rig, the top drive assembly including a drive shaft, the top
drive assembly being operative to rotate the drive shaft, the pipe
running tool comprising: a lower pipe engagement assembly
comprising: a housing defining a central passageway sized for
receipt of a pipe segment, the housing being coupled to the top
drive assembly for rotation therewith; a plurality of slips
disposed within the housing and displaceable between disengaged and
engaged positions; and a powered system connected to the respective
slips and operative to selectively drive the slips between the
disengaged and engaged positions.
11. The pipe running tool of claim 10, further including a hoist
mechanism connected to the lower pipe engagement assembly and
operative to hoist a pipe segment into the central passageway of
the lower pipe engagement assembly.
12. The pipe running tool of claim 11, wherein the hoist mechanism
comprises an axle journaled to the lower pipe engagement member, a
pair of pulleys rotatably mounted to the axle, and a gear connected
to the axle, whereby the gear may be coupled to a drive system for
rotating the axle.
13. The pipe running tool of claim 10, wherein the powered system
comprises one of a hydraulic and pneumatic system.
14. The pipe running tool of claim 10, further including a block
connected to the top drive assembly and adapted for engaging a
plurality of cables connected to the rig.
15. In a system for assembling a pipe string comprising a top drive
assembly, a lower pipe engagement assembly coupled to the top drive
assembly for rotation therewith and operative to releasably engage
a pipe segment, and a load compensator operative to raise the lower
pipe engagement assembly relative to the top drive assembly, a
method for threadedly engaging a pipe segment with a pipe string,
comprising the steps of: actuating the lower pipe engagement
assembly to releasably engage a pipe segment; lowering the top
drive assembly to bring the pipe segment into contact with the pipe
string; monitoring the load on the pipe string; actuating the load
compensator to raise the pipe segment a selected distance relative
to the pipe string, if the load on the pipe string exceeds a
predetermined threshold value; and actuating the top drive assembly
to rotate the pipe segment to threadedly engage the pipe segment
and pipe string.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to well drilling operations and, more
particularly, to a device for assisting in the assembly of pipe
strings, such as casing strings, drill strings and the like.
2. Description of the Related Art
The drilling of oil wells involves assembling drill strings and
casing strings, each of which comprises a plurality of elongated,
heavy pipe segments extending downwardly from an oil drilling rig
into a hole. The drill string consists of a number of sections of
pipe which are threadedly engaged together, with the lowest segment
(i.e., the one extending the furthest into the hole) carrying a
drill bit at its lower end. Typically, the casing string is
provided around the drill string to line the well bore after
drilling the hole and ensure the integrity of the hole. The casing
string also consists of a plurality of pipe segments which are
threadedly coupled together and formed with through passages sized
to receive the drill string and/or other pipe strings.
The conventional manner in which plural casing segments are coupled
together to form a casing string is a labor-intensive method
involving the use of a "stabber" and casing tongs. The stabber is
manually controlled to insert a segment of casing into the upper
end of the existing casing string, and the tongs are designed to
engage and rotate the segment to threadedly connect it to the
casing string. While such a method is effective, it is cumbersome
and relatively inefficient because the procedure is done manually.
In addition, the casing tongs require a casing crew to properly
engage the segment of casing and to couple the segment to the
casing string. Thus, such a method is relatively labor-intensive
and therefore costly. Furthermore, using casing tongs requires the
setting up of scaffolding or other like structures, and is
therefore inefficient.
Others have proposed a casing running tool for assembling casing
strings which utilizes a conventional top drive assembly. The tool
includes a pivotable manipulator which is designed to engage a pipe
segment and raise the pipe segment up into a power assist spider,
which relies on gravity to hold the pipe segment. The spider is
coupled to the top drive and may be rotated by it. Thus, the pipe
segment may be brought into contact with a casing string and the
top drive activated to rotate the casing segment and threadedly
engage it with the casing string.
While such a system provides benefits over the more conventional
systems used to assemble casing strings, such a system suffers from
shortcomings. One such shortcoming is that the casing segment may
not be sufficiently engaged by the power assist spider to properly
connect the casing segment with the casing string. In addition, the
system fails to provide any means for effectively controlling the
load applied to the threads at the bottom of the casing segment.
Without the ability to control the load on the threads,
cross-threading may occur, resulting in stripped threads and a
useless casing segment.
Accordingly, it will be apparent to those skilled in the art that
there continues to be a need for a device for use in a drilling
system which utilizes an existing top drive assembly to efficiently
assemble casing and/or drill strings, and which positively engages
a pipe segment to ensure proper coupling of the pipe segment to a
pipe string. The present invention addresses these needs and
others.
SUMMARY OF THE INVENTION
Briefly, and in general terms, the present invention is directed to
a pipe running tool for use in drilling systems and the like to
assemble casing and/or drill strings. The pipe running tool is
coupled to an existing top drive assembly which is used to rotate a
drill string, and includes a powered elevator that is powered into
an engaged position to securely engage a pipe segment, for example,
a casing segment. Because the elevator is powered into the engaged
position, the pipe segment may be properly coupled to an existing
pipe string using the top drive assembly.
The system of the present invention in one illustrative embodiment
is directed to a pipe running tool mountable on a rig and
including: a top drive assembly adapted to be connected to the rig
for vertical displacement of the top drive assembly relative to the
rig, the top drive assembly including a drive shaft, the top drive
assembly being operative to rotate the drive shaft; and a lower
pipe engagement assembly including a central passageway sized for
receipt of the pipe segment, the lower pipe engagement assembly
including a powered engagement device that is powered to an engaged
position to securely and releasably grasp the pipe segment, the
lower pipe engagement assembly being in communication with the
drive shaft, whereby actuation of the top drive assembly causes the
lower pipe engagement assembly to rotate.
In another illustrative embodiment, the present invention is
directed to a method of assembling a pipe string, including the
steps of: actuating a lower pipe engagement assembly to releasably
engage a pipe segment; lowering a top drive assembly to bring the
pipe segment into contact with a pipe string; monitoring the load
on the pipe string; actuating a load compensator to raise the pipe
segment a selected distance relative to the pipe string, if the
load on the pipe string exceeds a predetermined threshold value;
and actuating the top drive assembly to rotate the pipe segment to
threadedly engage the pipe segment and pipe string.
Other features and advantages of the present invention will become
apparent from the following detailed description, taken in
conjunction with the accompanying drawings which illustrate, by way
of example, the features of the present invention.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is an elevated side view of a drilling rig incorporating a
pipe running tool according to one illustrative embodiment of the
present invention;
FIG. 2 is a side view, in enlarged scale, of the pipe running tool
of FIG. 1;
FIG. 3 is a cross-sectional view taken along the line 3--3 of FIG.
2;
FIG. 4 is a cross-sectional view taken along the line 4--4 of FIG.
2;
FIG. 5A is a cross-sectional view taken along the line 5--5 of FIG.
4 and showing a spider/elevator in a disengaged position;
FIG. 5B is a cross-sectional view similar to FIG. 5A and showing
the spider/elevator in an engaged position;
FIG. 6 is a block diagram of components included in one
illustrative embodiment of the invention; and
FIG. 7 is a side view of another illustrative embodiment of the
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the following detailed description, like reference numerals will
be used to refer to like or corresponding elements in the different
figures of the drawings. Referring now to FIGS. 1 and 2, there is
shown a pipe running tool 10 depicting one illustrative embodiment
of the present invention, which is designed for use in assembling
pipe strings, such as drill strings, casing strings, and the like.
The pipe running tool 10 comprises, generally, a frame assembly 12,
a rotatable shaft 14, and a lower pipe engagement assembly 16 that
is coupled to the rotatable shaft for rotation therewith. The pipe
engagement assembly is designed for selective engagement of a pipe
segment 11 (FIGS. 1, 2, and 5A) to substantially prevent relative
rotation between the pipe segment and the pipe engagement assembly.
The rotatable shaft 14 is designed for coupling with a top drive
output shaft from an existing top drive, such that the top drive,
which is normally used to rotate a drill string to drill a well
hole, may be used to assemble a pipe string, for example, a casing
string or a drill string, as is described in greater detail
below.
The pipe running tool 10 is designed for use, for example, in a
well drilling rig 18. A suitable example of such a rig is disclosed
in U.S. Pat. No. 4,765,401 to Boyadjieff, which is expressly
incorporated herein by reference as if fully set forth herein. As
shown in FIG. 1, the rig includes a frame 20 and a pair of guide
rails 22 along which a top drive assembly, generally designated 24,
may ride for vertical movement relative to the rig. The top drive
assembly is preferably a conventional top drive used to rotate a
drill string to drill a well hole, as is described in U.S. Pat. No.
4,605,077 to Boyadjieff, which is expressly incorporated herein by
reference. The top drive assembly includes a drive motor 26 and a
top drive output shaft 28 extending downwardly from the drive
motor, with the drive motor being operative to rotate the drive
shaft, as is conventional in the art. The rig defines a drill floor
30 having a central opening 32 through which a drill string and/or
casing string 34 is extended downwardly into a well hole.
The rig 18 also includes a flush-mounted spider 36 that is
configured to releasably engage the drill string and/or casing
string 34 and support the weight thereof as it extends downwardly
from the spider into the well hole. As is well known in the art,
the spider includes a generally cylindrical housing which defines a
central passageway through which the pipe string may pass. The
spider includes a plurality of slips which are located within the
housing and are selectively displaceable between disengaged and
engaged positions, with the slips being driven radially inwardly to
the respective engaged positions to tightly engage the pipe segment
and thereby prevent relative movement or rotation of the pipe
segment and the spider housing. The slips are preferably driven
between the disengaged and engaged positions by means of a
hydraulic or pneumatic system, but may be driven by any other
suitable means.
Referring primarily to FIG. 2, the pipe running tool 10 includes
the frame assembly 12, which comprises a pair of links 40 extending
downwardly from a link adapter 42. The link adapter defines a
central opening 44 through which the top drive output shaft 28 may
pass. Mounted to the link adapter on diametrically opposed sides of
the central opening are respective upwardly extending, tubular
members 46 (FIG. 1), which are spaced a predetermined distance
apart to allow the top drive output shaft 28 to pass therebetween.
The respective tubular members connect at their upper ends to a
rotating head 48, which is connected to the top drive assembly 24
for movement therewith. The rotating head defines a central opening
(not shown) through which the top drive output shaft may pass, and
also includes a bearing (not shown) which engages the upper ends of
the tubular members and permits the tubular members to rotate
relative to the rotating head body, as is described in greater
detail below.
The top drive output shaft 28 terminates at its lower end in an
internally splined coupler 52 which is engaged to an upper end of
the lower drive shaft 14 (not shown) which is formed to complement
the splined coupler for rotation therewith. Thus, when the top
drive output shaft 28 is rotated by the top drive motor 26, the
lower drive shaft 14 is also rotated. It will be understood that
any suitable interface may be used to securely engage the top and
lower drive shafts together.
In one illustrative embodiment, the lower drive shaft 14 is
connected to a conventional pipe handler, generally designated 56,
which may be engaged by a suitable torque wrench (not shown) to
rotate the lower drive shaft and thereby make and break connections
that require very high torque, as is well known in the art.
The lower drive shaft 14 is also formed with a splined segment 58,
which is slidably received in an elongated, splined bushing 60
which serves as an extension of the lower drive shaft. The drive
shaft and bushing are splined to provide for vertical movement of
the shaft relative to the bushing, as is described in greater
detail below. It will be understood that the splined interface
causes the bushing to rotate when the lower drive shaft
rotates.
The pipe running tool 10 further includes the lower pipe engagement
assembly 16, which in one embodiment comprises a torque transfer
sleeve 62 which is securely connected to the lower end of the
bushing 60 for rotation therewith. The torque transfer sleeve is
generally annular and includes a pair of upwardly projecting arms
64 on diametrically opposed sides of the sleeve. The arms are
formed with respective horizontal through passageways (not shown)
into which are mounted respective bearings (not shown) which serve
to journal a rotatable axle 70 therein, as described in greater
detail below. The transfer sleeve connects at its lower end to a
downwardly extending torque frame 72 in the form of a pair of
tubular members 73, which in turn is coupled to a spider/elevator
74 which rotates with the torque frame. It will be apparent that
the torque frame may take many, such as a plurality of tubular
members, a solid body, or any other suitable structure.
The spider/elevator 74 is preferably powered by a hydraulic or
pneumatic system, or alternatively by an electric drive motor or
any other suitable powered system. In the embodiment disclosed, the
spider/elevator includes a housing 75 which defines a central
passageway 76 through which the pipe segment 11 may pass. The
spider/elevator also includes a pair of hydraulic or pneumatic
cylinders 77 with displaceable piston rods 78 (FIGS. 5A and 5B)
which are connected through suitable pivotable linkages 79 to
respective slips 80. The linkages are pivotally connected to both
the top ends of the piston rods and to the top ends of the slips.
The slips include generally planar front gripping surfaces 82, and
specially contoured rear surfaces 84 which are designed with such a
contour to cause the slips to travel between respective radially
outwardly disposed, disengaged positions, and radially inwardly
disposed, engaged positions. The rear surfaces of the slips travel
along respective downwardly and radially inwardly projecting
guiding members 86 which are complementarily contoured and securely
connected to the spider body. The guiding members cooperate with
the cylinders and linkages to cam the slips radially inwardly and
force the slips into the respective engaged positions. Thus, the
cylinders (or other actuating means) may be empowered to drive the
piston rods downwardly, causing the corresponding linkages to be
driven downwardly and therefore force the slips downwardly. The
surfaces of the guiding members are angled to force the slips
radially inwardly as they are driven downwardly to sandwich the
pipe segment 11 between them, with the guiding members maintaining
the slips in tight engagement with the pipe segment. To release the
pipe segment 11, the cylinders 76 are operated in reverse to drive
the piston rods upwardly, which draws the linkages upwardly and
retracts the respective slips back to their disengaged positions to
release the pipe segment. The guiding members are preferably formed
with respective notches 81 which receive respective projecting
portions 83 of the slips to lock the slips in the disengaged
position (FIG. 5A).
The spider/elevator 74 further includes a pair of diametrically
opposed, outwardly projecting ears 88 formed with downwardly facing
recesses 90 sized to receive correspondingly formed, cylindrical
members 92 at the bottom ends of the respective links 40, and
thereby securely connect the lower ends of the links to the
spider/elevator. The ears may be connected to an annular sleeve 93
which is received over the housing 75, or may be formed integral
with the housing.
In one illustrative embodiment, the pipe running tool 10 includes a
load compensator, generally designated 94. The load compensator
preferably is in the form of a pair of hydraulic, double rodded
cylinders 96, each of which includes a pair of piston rods 98 that
are selectively extendable from, and retractable into, the
cylinder. The upper rods connect to a compensator clamp 100, which
in turn is connected to the lower drive shaft 14, while the lower
rods extend downwardly and connect at the respective lower ends to
a pair of ears 102 which are securely mounted to the bushing 60.
The hydraulic cylinders may be actuated to draw the bushing
upwardly relative to the lower drive shaft 14 by applying a
pressure to the cylinders which causes the upper piston rods to
retract into the respective cylinder bodies, with the splined
interface between the bushing and lower drive shaft allowing the
bushing to be displaced vertically relative to the shaft. In that
manner, the pipe segment 11 carried by the spider/elevator 74 may
be raised vertically to relieve a portion or all of the load
applied to the pipe segment 11, as is described in greater detail
below. As is shown in FIG. 2, the lower rods are at least partially
retracted, resulting in the majority of the load from the pipe
running tool 10 is assumed by the top drive output shaft 28. In
addition, when a load above a preselected maximum is applied to the
pipe segment 11, the cylinders 96 will automatically react the load
to prevent the entire load from being applied to the threads of the
pipe segment.
The pipe running tool 10 still further includes a hoist mechanism,
generally designated 104, for hoisting a pipe segment upwardly into
the spider/elevator 74. The hoist mechanism is disposed off-axis
and includes a pair of pulleys 106 carried by the axle 70, the axle
being journaled into the bearings in respective through passageways
formed in the arms 64. The hoist mechanism also includes a gear
drive, generally designated 108, that may be selectively driven by
a hydraulic motor 111 or other suitable drive system to rotate the
axle and thus the pulleys. The hoist may also include a brake 115
to prevent rotation of the axle and therefore of the pulleys and
lock them in place, as well as a torque hub 116. Therefore, a pair
of chains, cables, or other suitable, flexible means may be run
over the respective pulleys, extended through a chain well 113, and
engaged to the pipe segment 11, and the axle is then rotated by a
suitable drive system to hoist the pipe segment vertically and up
into position with the upper end of the pipe segment 11 extending
into the spider/elevator 74.
The pipe running tool 10 preferably further includes an annular
collar 109 which is received over the links 40 and which maintains
the links locked to the ears 88 and prevents the links from
twisting and/or winding.
In use, a work crew may manipulate the pipe running tool 10 until
the upper end of the tool is aligned with the lower end of the top
drive output shaft 28. The pipe running tool 10 is then raised
vertically until the splined coupler 52 at the lower end of the top
drive output shaft is engaged to the upper end of the lower drive
shaft 14 and the links 40 are engaged with the ears 93. The work
crew may then run a pair of chains or cables over the respective
pulleys 106 of the hoist mechanism 104, connect the chains or
cables to a pipe segment 11, engage a suitable drive system to the
gear 108, and actuate the drive system to rotate the pulleys and
thereby hoist the pipe segment upwardly until the upper end of the
pipe segment extends, through the lower end of the spider/elevator
74. The spider/elevator is then actuated, with the hydraulic
cylinders 77 and guiding members 86 cooperating to forcibly drive
the respective slips 84 into the engaged positions (FIG. 5B) to
positively engage the pipe segment. The slips are preferably
advanced to a sufficient extent to prevent relative rotation
between the pipe segment and the spider/elevator, such that
rotation of the spider/elevator translates into rotation of the
pipe segment.
The top drive assembly 24 is then lowered relative to the frame 20
by means of the top hoist 25 to drive the threaded lower end of the
pipe segment 11 into contact with the threaded upper end of the
pipe string 34 (FIG. 1). As shown in FIG. 1, the pipe string is
securely held in place by means of the flush-mounted spider 36 or
any other suitable structure for securing the string in place, as
is well known to those skilled in the art. Once the threads are
properly mated, the top drive motor 26 is then actuated to rotate
the top drive output shaft, which in turn rotates the lower drive
shaft of the pipe running tool 10 and the spider/elevator 74, which
causes the coupled pipe segment to rotate and thereby be threadedly
engaged to the pipe string.
In one embodiment, the pipe segment 11 is intentionally lowered
until the lower end of the pipe segment rests on the top of the
pipe string 34. The load compensator 94 is then actuated to drive
the bushing 60 upwardly relative to the lower drive shaft 14 via
the splined interface between the two. The upward movement of the
bushing causes the spider/elevator 74 and therefore the coupled
pipe segment 11 to be raised, thereby reducing the weight on the
threads of the pipe segment. In this manner, the load on the
threads can be controlled by actuating the load compensator.
Once the pipe segment 11 is threadedly coupled to the pipe string,
the top drive assembly 24 is raised vertically to lift the entire
pipe string 34, which causes the flush-mounted spider 36 to
disengage the string. The top drive assembly 24 is then lowered to
advance the string downwardly into the well hole until the upper
end of the top pipe segment 11 is close to the drill floor 30, with
the entire load of the pipe string being carried by the links 40
while the torque was supplied through shafts. The flush-mounted
spider 36 is then actuated to engage the pipe string and suspend it
therefrom. The spider/elevator 74 is then controlled in reverse to
retract the slips 84 back to the respective disengaged positions
(FIG. 5A) to release the pipe string. The top drive assembly 24 is
then raised to lift the pipe running tool 10 up to a starting
position (such as that shown in FIG. 1) and the process may be
repeated with an additional pipe segment 11.
Referring to FIG. 6, there is shown a block diagram of components
included in one illustrative embodiment of the pipe running tool
10. In this embodiment, the tool includes a conventional load cell
110 or other suitable load-measuring device mounted on the pipe
running tool 10 in such a manner that it is in communication with
the lower drive shaft 14 to determine the load applied to the lower
end of the pipe segment 11. The load cell is operative to generate
a signal representing the load sensed, which in one illustrative
embodiment is transmitted to a processor 112. The processor is
programmed with a predetermined threshold load value, and compares
the signal from the load cell with that value. If the load exceeds
the value, the processor then controls the load compensator 94 to
draw upwardly a selected amount to relieve at least a portion of
the load on the threads of the pipe segment. Once the load is at or
below the threshold value, the processor controls the top drive
assembly 24 to rotate the pipe segment 11 and thereby threadedly
engage the pipe segment to the pipe string 34. While the top drive
assembly is actuated, the processor continues to monitor the
signals from the load cell to ensure that the load on the pipe
segment does not exceed the threshold value.
Alternatively, the load on the pipe segment 11 may be controlled
manually, with the load cell 110 indicating the load on the pipe
segment via a suitable gauge or other display, with a work person
controlling the load compensator 94 and top drive assembly 24
accordingly.
Referring to FIG. 7, there is shown another preferred embodiment of
the pipe running tool 200 of the present invention. The pipe
running tool includes a hoisting mechanism 202 which is
substantially the same as the hoisting mechanism 104 described
above. A lower drive shaft 204 is provided and connects at its
lower end to a conventional mud-filling device 206 which, as is
known in the art, is used to fill a pipe segment, for example, a
casing segment, with mud during the assembly process. In one
illustrative embodiment, the mud-filling device is a device
manufactured by Davies-Lynch Inc. of Texas.
The hoisting mechanism 202 supports a pair of chains 208 which
engage a slip-type single joint elevator 210 at the lower end of
the pipe running tool 200. As is known in the art, the single joint
elevator is operative to releasably engage a pipe segment 11, with
the hoisting mechanism 202 being operative to raise the single
joint elevator and pipe segment upwardly and into the
spider/elevator 74.
The tool 200 includes the links 40 which define the cylindrical
lower ends 92 which are received in generally J-shaped cut-outs 212
formed in diametrically opposite sides of the spider/elevator
74.
From the foregoing, it will be apparent that the pipe running tool
10 efficiently utilizes an existing top drive assembly to assemble
a pipe string, for example, a casing or drill string, and does not
rely on cumbersome casing tongs and other conventional devices. The
pipe running tool incorporates the spider/elevator 74, which not
only carries pipe segments, but also imparts rotation to them to
threadedly engage the pipe segments to an existing pipe string.
Thus, the pipe running tool provides a device which grips and
torques the pipe segment 11, and which also is capable of
supporting the entire load of the pipe string as it is lowered down
into the well hole.
While several forms of the present invention have been illustrated
and described, it will be apparent to those of ordinary skill in
the art that various modifications and improvements can be made
without departing from the spirit and scope of the invention.
Accordingly, it is not intended that the invention be limited,
except as by the appended claims.
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